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dc.contributor.authorSiegert, T.
dc.contributor.authorDiehl, R.
dc.contributor.authorVincent, A.~C.
dc.contributor.authorGuglielmetti, F.
dc.contributor.authorKrause, M.~G.~H.
dc.contributor.authorBoehm, C.
dc.date.accessioned2016-11-18T15:42:02Z
dc.date.available2016-11-18T15:42:02Z
dc.date.issued2016-10-24
dc.identifier.citationSiegert , T , Diehl , R , Vincent , A C , Guglielmetti , F , Krause , M G H & Boehm , C 2016 , ' Search for 511 keV Emission in Satellite Galaxies of the Milky Way with INTEGRAL/SPI ' , Astronomy & Astrophysics , vol. 595 , A25 . https://doi.org/10.1051/0004-6361/201629136
dc.identifier.issn0004-6361
dc.identifier.otherPURE: 10546633
dc.identifier.otherPURE UUID: e7a82712-5950-463c-b14a-c63e177de2a0
dc.identifier.otherBibtex: urn:a9a639221c3e10f79396d038518e7ce7
dc.identifier.otherScopus: 84994045117
dc.identifier.otherORCID: /0000-0002-9610-5629/work/63687409
dc.identifier.urihttp://hdl.handle.net/2299/17333
dc.descriptionReproduced with permission from Astronomy & Astrophysics. © 2018 ESO.
dc.description.abstractThe positron annihilation gamma-ray signal in the Milky Way (MW) shows a puzzling morphology: a very bright bulge and a very low surface-brightness disk. A coherent explanation of the positron origin, propagation through the Galaxy and subsequent annihilation in the interstellar medium has not yet been found. Tentative explanations involve positrons from radioactivity, X-ray binaries, and dark matter (DM). Dwarf satellite galaxies (DSGs) are believed to be DM-dominated and hence promising candidates in the search for 511 keV emission as a result of DM annihilation into electron-positron pairs. The goal of this study is to constrain possible 511 keV gamma-ray signals from 39 DSGs of the MW and to test the annihilating DM scenario. We use the spectrometer SPI on INTEGRAL to extract individual spectra for the studied objects. As the diffuse galactic emission dominates the signal, the large scale morphology of the MW has been modelled accordingly and was included in a maximum likelihood analysis. Alternatively, a distance-weighted stacked spectrum has been determined. Only Reticulum II (Ret II) shows a 3.1 sigma signal. Five other sources show tentative 2 sigma signals. The mass-to-511-keV-luminosity-ratio shows a marginal trend towards higher values for intrinsically brighter objects, opposite to the V band mass-to-light-ratio, which is generally used to uncover DM in DSGs. All derived flux values are above the level implied by a DM interpretation of the MW bulge signal. The signal from Ret II is unlikely to be related to a DM origin alone, otherwise, the MW bulge would be about 100 times brighter than what is seen. Ret II is exceptional considering the DSG sample, and rather points to enhanced recent star formation activity, if its origins are similar to processes in the MW. Understanding this emission may provide further clues regarding the origin of the annihilation emission in the MW.en
dc.format.extent7
dc.language.isoeng
dc.relation.ispartofAstronomy & Astrophysics
dc.subjectAstrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
dc.titleSearch for 511 keV Emission in Satellite Galaxies of the Milky Way with INTEGRAL/SPIen
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.contributor.institutionCentre for Astrophysics Research
dc.description.statusPeer reviewed
dc.identifier.urlhttps://arxiv.org/pdf/1608.00393v1.pdf
rioxxterms.versionVoR
rioxxterms.versionofrecordhttps://doi.org/10.1051/0004-6361/201629136
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue


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